linux-kernel - Re: [PATCH RFC net-next] net: phylink: always config mac for (delayed) phy

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Message-ID: <4b9b2a9a-061b-43ad-b402-a49aee317f41@gmail.com>
Date: Tue, 7 Jan 2025 14:14:03 +0100
From: Eric Woudstra <ericwouds@...il.com>
To: "Russell King (Oracle)" <linux@...linux.org.uk>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Matthias Brugger <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 Frank Wunderlich <frank-w@...lic-files.de>,
 Daniel Golle <daniel@...rotopia.org>, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, netfilter-devel@...r.kernel.org,
 coreteam@...filter.org, bridge@...ts.linux.dev,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH RFC net-next] net: phylink: always config mac for
 (delayed) phy



On 1/7/25 1:47 PM, Russell King (Oracle) wrote:
> Going through the log...
> 
> On Tue, Jan 07, 2025 at 01:36:15PM +0100, Eric Woudstra wrote:
>> Log before this patch is applied:
>> [root@...r3 ~]# dmesg | grep eth1
>> [    2.515179] mtk_soc_eth 15100000.ethernet eth1: mediatek frame engine at 0xffff800082380000, irq 123
>> [   38.271431] mtk_soc_eth 15100000.ethernet eth1: configuring for inband/2500base-x link mode
>> [   38.279828] mtk_soc_eth 15100000.ethernet eth1: major config, requested inband/2500base-x
>> [   38.288009] mtk_soc_eth 15100000.ethernet eth1: interface 2500base-x inband modes: pcs=01 phy=00
>> [   38.296800] mtk_soc_eth 15100000.ethernet eth1: major config, active inband/inband,an-disabled/2500base-x
> 
> This is indeed without the PHY. We're using inband, although the PCS
> mode is PHYLINK_PCS_NEG_INBAND_DISABLED, meaning inband won't be
> used. As there is no PHY, we can't switch to MLO_AN_PHY.
> 
>> [   38.306362] mtk_soc_eth 15100000.ethernet eth1: phylink_mac_config: mode=inband/2500base-x/none adv=00,00000000,00008000,0000e240 pause=04
>> [   39.220149] mtk_soc_eth 15100000.ethernet eth1:  interface 2 (mii) rate match none supports 0-3,6-7,13-14
>> [   39.229758] mtk_soc_eth 15100000.ethernet eth1:  interface 3 (gmii) rate match none supports 0-3,5-7,13-14
>> [   39.239420] mtk_soc_eth 15100000.ethernet eth1:  interface 4 (sgmii) rate match none supports 0-3,5-7,13-14
>> [   39.249173] mtk_soc_eth 15100000.ethernet eth1:  interface 22 (1000base-x) rate match none supports 5-7,13-14
>> [   39.259080] mtk_soc_eth 15100000.ethernet eth1:  interface 23 (2500base-x) rate match none supports 6-7,13-14,47
>> [   39.594676] mtk_soc_eth 15100000.ethernet eth1: PHY i2c:sfp-1:11 uses interfaces 4,23, validating 4,23
> 
> The PHY comes along...
> 
>> [   39.603992] mtk_soc_eth 15100000.ethernet eth1:  interface 4 (sgmii) rate match none supports 0-3,5-7,13-14
>> [   39.650080] mtk_soc_eth 15100000.ethernet eth1:  interface 23 (2500base-x) rate match none supports 6-7,13-14,47
>> [   39.660266] mtk_soc_eth 15100000.ethernet eth1: PHY [i2c:sfp-1:11] driver [RTL8221B-VB-CG 2.5Gbps PHY (C45)] (irq=POLL)
>> [   39.671037] mtk_soc_eth 15100000.ethernet eth1: phy: 2500base-x setting supported 00,00000000,00008000,000060ef advertising 00,00000000,00008000,000060ef
>> [   39.684761] mtk_soc_eth 15100000.ethernet eth1: requesting link mode inband/2500base-x with support 00,00000000,00008000,000060ef
> 
> We decide to use MLO_AN_INBAND and 2500base-X, which we're already using.
> 
>> [   40.380076] mtk_soc_eth 15100000.ethernet eth1: phy link down 2500base-x/Unknown/Unknown/none/off
>> [   40.397090] brlan: port 5(eth1) entered blocking state
>> [   40.402223] brlan: port 5(eth1) entered disabled state
>> [   40.407437] mtk_soc_eth 15100000.ethernet eth1: entered allmulticast mode
>> [   40.414400] mtk_soc_eth 15100000.ethernet eth1: entered promiscuous mode
>> [   44.500077] mtk_soc_eth 15100000.ethernet eth1: phy link up 2500base-x/2.5Gbps/Full/none/off
>> [   44.508528] mtk_soc_eth 15100000.ethernet eth1: No phy led trigger registered for speed(2500)
> 
> ... but we don't see link-up reported by the PCS after the PHY comes
> up. Why is that - I think that needs investigation before we proceed
> to patch the issue, because that suggests the PCS isn't seeing
> valid 2500base-X from the PHY.
> 

I think it is because pl->act_link_an_mode stays at MLO_AN_INBAND, but
it needs to be set to MLO_AN_PHY, so that only the phy determines the
link state:

phylink_resolve() {
    ...
	} else if (pl->act_link_an_mode == MLO_AN_PHY) {
		link_state = pl->phy_state;
    ...
}